The Electron Transfer Series [MoIII(bpy)3]n (n=3+, 2+, 1+, 0, 1−), and the Dinuclear Species [{MoIIICl(Mebpy)2}2(μ2‐O)]Cl2 and [{MoIV(tpy.)2}2(μ2‐MoO4)](PF6)2⋅4 MeCN

The electronic structures of the five members of the electron transfer series [Mo(bpy)₃]ⁿ (n=3+, 2+, 1+, 0, 1?) are determined through a combination of techniques: electro‐ and magnetochemistry, UV/Vis and EPR spectroscopies, and X‐ray crystallography. The mono‐ and dication are prepared and isolated as PF₆ salts for the first time. It is shown that all species contain a central Mo^III ion (4d³). The successive one‐electron reductions/oxidations within the series are all ligand‐based, involving neutral (bpy⁰), the π‐radical anion (bpy^.)^1?, and the diamagnetic dianion (bpy^2?)^2?: [Mo^III(bpy⁰)₃]³⁺ (S=3/2), [Mo^III(bpy^.)(bpy⁰)₂]²⁺ (S=1), [Mo^III(bpy^.)₂(bpy⁰)]¹⁺ (S=1/2), [Mo^III(bpy^.)₃] (S=0), and [Mo^III(bpy^.)₂(bpy^2?)]^1? (S=1/2). The previously described diamagnetic dication “[Mo^II(bpy⁰)₃](BF₄)₂” is proposed to be a diamagnetic dinuclear species [{Mo(bpy)₃}₂(μ₂‐O)](BF₄)₄. Two new polynuclear complexes are prepared and structurally characterized: [{Mo^IIICl(^Mebpy⁰)₂}₂(μ₂‐O)]Cl₂ and [{Mo^IV(tpy^.)₂}₂(μ₂‐Mo^VIO₄)](PF₆)₂?4 MeCN.     

Single‐Layered Ultrasmall Nanoplates of MoS2 Embedded in Carbon Nanofibers with Excellent Electrochemical Performance for Lithium and Sodium Storage

The preparation and electrochemical storage behavior of MoS₂ nanodots—more precisely single‐layered ultrasmall nanoplates—embedded in carbon nanowires has been studied. The preparation is achieved by an electrospinning process that can be easily scaled up. The rate performance and cycling stability of both lithium and sodium storage were found to be outstanding. The storage behavior is, moreover, highly exciting from a fundamental point of view, as the differences between the usual storage modes—insertion, conversion, interfacial storage—are beneficially blurred. The restriction to ultrasmall reaction domains allows for an almost diffusion‐less and nucleation‐free “conversion”, thereby resulting in a high capacity and a remarkable cycling performance.     

介孔碳担载的 Co-Mo 和 Ni-Mo 加氢脱硫催化剂

 自制介孔碳 (CMC) 具有比传统活性碳 (AC) 更大的比表面积、孔径和孔体积, 以其为载体, 在浸渍液中加入螯合剂, 采用等量浸渍法制备了 Co-Mo/CMC 和 Ni-Mo/CMC 催化剂, 分别用于模型汽油和柴油加氢脱硫反应. 结果表明, Co-Mo/CMC 和 Ni-Mo/CMC 催化剂具有比 Co-Mo/AC 催化剂更好的织构性质和加氢脱硫活性. 在模型汽油的加氢脱硫反应中, Co-Mo/CMC 催化剂活性比工业催化剂 Co-Mo/Al2O3 高得多; 而在模型柴油的加氢脱硫反应中, Ni-Mo/CMC 催化剂活性也比工业催化剂 FH-98 高得多.     

Interaction of Mo(CO)6 and its derivative fragments with the Cu(001) surface: Influence on the decomposition process

A theoretical study on the adsorption and decomposition of molybdenum carbonyl on the copper (001) surface is reported. The adsorption structures and energies of Mo(CO)_n molecules (n = 1 … 6) are computed systematically using density functional theory with Van der Waals corrections. By analyzing the energies of the various conformations, the main factors that determine the stable adsorption geometry are identified. Insight into the thermodynamics of decomposition is gained by calculating the reaction energy for dissociation of Mo(CO)_n into Mo(CO)_n?1 and CO. In the gas phase, this reaction is highly endothermic for all n. On the Cu surface, however, removal of the first CO group (n = 6) becomes strongly exothermic. The subsequent dissociation steps (n < 6), are endothermic even on the surface, but the reaction energies are much reduced. Dissociation is found energetically more favorable than desorption in all cases. The results clearly show that molybdenum carbonyl decomposition is strongly facilitated by the presence of the Cu surface. © 2014 Wiley Periodicals, Inc.     

Two‐Dimensional Core‐Shelled Porous Hybrids as Highly Efficient Catalysts for the Oxygen Reduction Reaction

Two‐dimensional (2D) transition‐metal dichalcogenides (TMDs) have drawn much attention due to their unique physical and chemical properties. Using TMDs as templates for the generation of 2D sandwich‐like materials with remarkable properties still remains a great challenge due to their poor solvent processability. Herein, MoS₂‐coupled sandwich‐like conjugated microporous polymers (M‐CMPs) with high specific surface area were successfully developed by using functionalized MoS₂ nanosheets as template. As‐prepared M‐CMPs were further used as precursors for preparation of MoS₂‐embedded nitrogen‐doped porous carbon nanosheets, which were revealed as novel electrocatalysts for oxygen reduction reaction with mainly four‐electron transfer mechanism and ultralow half‐wave potential in comparison with commercial Pt/C catalyst. Our strategy to core–shelled sandwich‐like hybrids paves a way for a new class of 2D hybrids for energy conversion and storage.     

Interface Engineering of MoS2/Ni3S2 Heterostructures for Highly Enhanced Electrochemical Overall‐Water‐Splitting Activity

To achieve sustainable production of H₂ fuel through water splitting, low‐cost electrocatalysts for the hydrogen‐evolution reaction (HER) and the oxygen‐evolution reaction (OER) are required to replace Pt and IrO₂ catalysts. Herein, for the first time, we present the interface engineering of novel MoS₂/Ni₃S₂ heterostructures, in which abundant interfaces are formed. For OER, such MoS₂/Ni₃S₂ heterostructures show an extremely low overpotential of ca. 218 mV at 10 mA cm^?2, which is superior to that of the state‐of‐the‐art OER electrocatalysts. Using MoS₂/Ni₃S₂ heterostructures as bifunctional electrocatalysts, an alkali electrolyzer delivers a current density of 10 mA cm^?2 at a very low cell voltage of ca. 1.56 V. In combination with DFT calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygen‐containing intermediates, thus accelerating the overall electrochemical water splitting.     

K-Co-Mo-C催化剂的制备及其合成低碳醇的性能

 采用溶胶-凝胶法制备了含碳的K-Co-Mo-C催化剂,通过改变碳前驱体的添加量以获得不同的碳含量,测试了催化剂上合成气制混合醇的性能. 结果表明,适量的残留碳增加了催化剂中活性相的分散度,提高了合成醇的收率和选择性,但过量的碳导致烃的选择性增加而醇的选择性下降,这是由于随着碳前驱体添加量的增加,催化剂中的Mo物种更容易被还原成金属态. 与惰性气氛中焙烧的样品不同,空气中焙烧的样品中没有碳的存在,氧化物组分容易生成难以还原的物相,合成醇活性较低. 含碳量为2.8%的样品具有最大的比表面积和孔体积,同时也具有最高的醇收率和选择性. 惰性气氛中高温焙烧样品导致其合成醇活性明显降低,但同时高碳醇的选择性增加.     

器外预硫化型MoNiP/γ-Al2O3催化剂的二苯并噻吩加氢脱硫活性

 制备了两种器外预硫化型MoNiP/γ-Al2O3催化剂,并以二苯并噻吩为模型化合物考察了其加氢脱硫(HDS)活性,选择了传统的器内预硫化催化剂作为参比. 采用X射线衍射(XRD)、 高分辨透射电镜(HRTEM)和X射线光电子能谱(XPS)等手段对二者在加氢活性相方面的差别进行了研究. 结果表明,器外预硫化催化剂的HDS活性(最高达到99%)与器内预硫化催化剂相当,但是其加氢能力相对较弱. XRD与HRTEM等研究表明,器外预硫化催化剂所形成的MoS2片晶的堆垛层数相对较低,而Mo与S元素的XPS分析结果则说明相对器内预硫化催化剂,器外预硫化催化剂中不但Mo的硫化度较低,而且MoS2活性相的含量亦较少,而二者活性相之间的这种差异应是导致两类催化剂加氢活性不同的主要原因.     

Synthesis and Characterization of a Reduced Molybdenum(V) Phosphate, (H_3dien)_2(H_2dien)_2[NaMo_(12)O_(24)(OH)_6-(H_2PO_4)(HPO_4)_5(PO_4)_2]·nH_2O (n = 10.92)

A new reduced molybdenum(V) phosphate (H3dien)2(H2dien)2[NaMo12O24 (OH)6 (H2PO4)(HPO4)5(PO4)2]·nH2O (n = 10.92, dien = diethylenetriamine) has been synthesized under hydrothermal conditions and characterized by elemental analyses, IR and X-ray diffraction. C16H96.84Mo12N12NaO72.92P8 (Mr = 3046.73) crystallizes in the monoclinic system, space group P21/c with a = 13.3575(18), b = 21.907(3), c = 15.654(2) , β = 110.22(2)°, V = 4298.4(10) 3, Dc = 2.354 g/cm3, Z = 2, μ(MoKα) = 1.966 mm-1, F(000) = 2990.4, the final R = 0.0357 and wR = 0.1086 for 8739 observed reflections with I > 2σ(I). It consists of sandwich-shaped cluster anions [Na{Mo6P4}2]10- held together into a three-dimensional supramolecular framework through intermolecular hydrogen-bonding contacts. A probe reaction of the oxidation of acetaldehyde with H2O2 showed that this compound has high catalytic activity in the reaction.